1. Field of the Invention
The present invention relates a substrate storage container for storing and transporting substrates such as semiconductor wafers, mask glass substrates, liquid crystal cells, recording media, etc., as well as a substrate storage container for use in positioning such a substrate with respect to a processing machine for shaping and processing it, transportation from one processing machine to another and/or storage for future use. Particularly, the present invention relates to an identification structure for a substrate storage container as well as an method of identifying a substrate storage container for identifying its process stage, the substrate storage container type, the number of substrates stored therein, and the like.
2. Description of the Prior Art
With serious price competition of semiconductor devices, development of substrates relating to semiconductor manufacturing, such as semiconductor wafers (to be referred to merely as wafers hereinbelow), mask glass substrates etc., into large size in diameter (e.g., 300 mm or 400 mm or greater) have proceeded rapidly in order to improve production yield and hence reduce the cost. At the same time, since semiconductor circuits have been increasingly miniaturized, highly clean conditions have been demanded not only for the factories where substrates are manufactured but also for substrate storage containers used for transportation of the substrates.
As a method for meeting such demands, there are proposed methods whereby substrates are transported, whilst being put in a closable substrate storage container, between a number of sites which are locally kept in highly clean conditions required for processing the substrates. Under such circumstances, development of substrate storage containers capable of being automatically conveyed without permitting the stored substrates to be contaminated and still directly accessible to the processing machine are in progress.
A substrate storage container 1 of wafers used for their transportation, reservation, positioning them to the processing machines, and the like comprises, as shown in FIGS. 1 and 2, a container body for holding a multiple number of wafers in alignment and a door element for sealingly closing the open front of the container body with a gasket interposed therebetween and is set to processing machine 30.
Attached to the undersurface of the container body is a bottom plate or bottom plate portion (to be referred generally to bottom plate hereinbelow). This bottom plate has a plurality of V-shaped grooves (kinematic couplings, hereafter V-shaped grooves), which function to position the container body when substrate storage container 1 is mounted to a processing machine 30. A gasket is interposed between the container body and door element to keep the sealed state of substrate storage container 1. A locking mechanism that is operable from the outside is incorporated in the door element and its engaging claws engage the open front of the container body creating sealed confinement.
A wafer processing machine 30 has a load port 31 for mounting substrate storage container 1, as shown in FIGS. 1 and 2. The surface of this load port 31 has a detecting means 32 for identification projections and single or multiple interlock pins 33, arranged apart from one another. This interlock pin 33 is to prevent substrate storage container 1 from being mounted and coupled erroneously.
In the above configuration, when wafers are processed and shaped, substrate storage container 1 is first mounted and coupled to load port 31 of processing machine 30 via its bottom plate. Then the locking mechanism of the door element is unlocked so that the engaging claws are disengaged from the engagement holes in the front side of the container body, whereby the door element that has closed the front side of the container body is removed. After removal of the door element, wafers are loaded from the inside of substrate storage container 1 and taken into processing machine 30, where the wafers are subjected to the predetermined process.
Generally, in semiconductor device manufacturing, in order to avoid contamination (adverse influences on wafer's characteristics due to adhesion of particles, organic molecules, inorganic molecules and the like to the wafer's surface) of the semiconductor storage containers 1 used before and after wafer's membrane forming, the substrate storage containers 1 to be used for handling the wafers before metal deposition are discriminated particularly from the substrate storage containers 1 to be used for storing the wafers after the treatment. From this viewpoint, a substrate storage container 1A to be used on the wafer loading side (to be referred to as a fore stage) in which wafers will be subjected to a metal deposition process is distinguished from a substrate storage container 1B to be used after metal deposition (to be referred to as an aft stage), by providing different identification projections and indentations as shown in FIGS. 1 and 2, thus providing easy identification.
FIGS. 1 and 2 are schematic diagrams showing substrate storage containers 1A and 1B with load ports 31 (31A and 31B) of processing machine 30. FIG. 1 shows a load port 31A of processing machine 30 in the fore stage and a substrate storage container 1A suited thereto. FIG. 2 shows a load port 31B of processing machine 30 in the aft stage and a substrate storage container 1B suited thereto.
As stated above, since the processing and shaping of wafers in semiconductor device manufacturing are complicated and manifold, substrate storage container 1 may be contaminated in some cases depending upon the wafers to be stored. For example, when the wafers at the fore stage is stored, uncontaminated substrate storage containers 1 are discriminated from contaminated substrate storage containers 1 and are used. Processing machine 30 or substrate processing equipment are designed so as to be able to handle all types of semiconductor storage containers 1 since it is assumed that various types of semiconductor storage containers 1 should be used depending upon various processing stages of wafers or depending upon semiconductor device manufactures. However, handling operations of substrate storage containers 1 in automation differ one from another depending upon the type of the substrate storage container 1, so that substrate storage containers 1 need to be discriminated and individual types handled selectively.
The types of substrate storage containers 1 include, for example, a closed container type called `FOUP` (Front Opening Unified Pod), a substrate shipping container type called `FOSB` (Front Opening Shipping Box) having almost the same configuration as a FOUP, and an open cassette type called `OC`. Each type of substrate storage container 1, further has two types, one which can hold thirteen wafers and the other which can hold twenty five wafers.
Accordingly, even with the same main part, substrate storage containers 1 have different specs of identification portions for discriminating one for the fore wafer processing stage from one for the aft wafer processing stage. Therefore, for manufacture of substrate storage containers 1, it is necessary to mold them by preparing two different metallic molds for molding substrate storage containers 1. Alternatively, it is necessary to provide a nesting configuration so that the identification portion can be replaced. However, these methods need multiple metallic molds and multiple die parts, resulting in large investment for the preparation of metallic molds. Further, it is difficult to identify the type of the container bodies formed by molding from their appearance, so that complicated production and inventory managements of the products are needed or there is a risk that type contamination may occur in the assembly and inspection stages of substrate storage containers 1.
Further, since the method heretofore has many complex stages, it has been very difficult for semiconductor device manufacturing using substrate storage containers 1 to exactly know which of the either substrate storage containers 1A, to be used for the fore stage or the substrate storage containers 1B to be used for the aft stage are lacking. Therefore, if substrate storage containers 1 are lacking, the manufacturer needs to order the substrate storage containers in short delivery intervals or needs to have two types of substrate storage containers 1A and 1B. Conventionally, for identifying the types of substrate storage containers 1A and 1B, and the number of wafers accommodated therein, an identification means such as of projections and indentations has been integrally formed with, or attached separately to, substrate storage container 1. These needed fixing such as by the use of screws, welding or the like and an extra step for assembly of substrate storage container 1.